1. Field of Invention
The present invention relates to a method for making a highly value-added refractory material and, more particularly, to a method for producing a refractory material including the steps of mixing aluminum residues with adhesive solution, granulating the mixture into grains, and forming the grains into a refractory material.
2. Related Prior Art
Waste aluminum is often recycled since the recycling of waste aluminum produces less pollution than the refinery of bauxite. At first, waste aluminum is collected. The waste aluminum is classified into new and used waste aluminum for example. The new waste aluminum includes burrs, scraps and disqualified products and takes up about 70 wt % of the waste aluminum. The used waste aluminum includes cables, parts of car bodies, cast products, cans and appliances. Then, the waste aluminum is generally melted in a small aluminum-melting furnace with a capacity of 1.5 to 7.5 ton/day. Finally, the melted aluminum is molded and made into aluminum nuggets.
Byproducts of the recycling of waste aluminum include aluminum residues that include dross and ash. An aluminum-recycling process includes the step of melting waste aluminum, the step of collecting the melted aluminum and the step of cooling. Exhaust from the aluminum-recycling process includes suspended particles that pollute the air. These suspended particles are collected by air pollution-preventing means in Donaldson DCE and the collected ash is generally called “white ash”, Murayama, N., Shibata, J., Sakai, K., Nakajima, S, and Yamamoto, H., “Synthesis of hydrotalcite-like materials from various wastes in aluminum regeneration process”, Resource Processing 53, pp. 6-11, 2006 or ash of secondary metallurgy of aluminum (or “aluminum ash”). The aluminum ash takes up about 1 wt % of the recycled waste aluminum. The aluminum ash includes Al2O3 and MgO and carbon released from the combustion of fuel in the aluminum-melting furnace. Moreover, there is dross floating on the melted aluminum in the aluminum-melting process. The dross includes metallic aluminum, aluminum oxide and aluminum nitride, depending on the components of the waste aluminum. The dross is about 15 wt % of the recycled waste aluminum. The dross or ash of the aluminum residues, including aluminum nitrides, absorbs water in the air and gets hydrolyzed. Hence, there is a stinky smell.
Currently, aluminum residues is neutralized and solidified before it is disposed of or buried, Hermsmeyer, D., Diekmann, R., Ploeg R. R. and Horton R., “Physical properties of a soil substitute derived from an aluminum recycling by-product”, Journal of Hazardous Materials B95, pp. 107-124, 2002; Shinzato, M. C. and Hypolito, R., “Solid waste from aluminum recycling process: characterization and reuse of its economically valuable constituents”, Waste Management 25, pp. 37-46, 2005; and Murayama, N., Arimura, K., Okajima, N. and Shibata, J., “Effect of structure-directing agent on AlPO4-n synthesis from aluminum dross”, International Journal of Mineral Processing 93, pp. 110-114, 2009.
Dross and ash are piled up or buried and will impose serious impacts on the environment and cause damage to human health if they are mishandled. Hence, neither piling up nor burial is good for handling the dross or ash. The dross and ash however possess commercial values. Therefore, there is a need for a method to recycle and use the dross and ash as zero waste and recycling are concerned.
As disclosed in Taiwanese Patent No. 583155, “Method for Using Aluminum Residues”, aluminum residues is heated and roasted into aluminum oxide (or “corundum”) that can be used as a refractory material.
As disclosed in Taiwanese Patent I319015, “Method for Recycling Secondary Aluminum Residues”, wet chemistry is used to add an oxidizing agent and sodium hydroxide to turn aluminum nitrides and fine metal powder into stable aluminum oxide. The method is however complicated.
On the other hand, refractory materials are generally made of mined natural substances. The use of such refractory materials increases the mining of such natural substances and the release of carbon dioxide during the mining, and imposes impacts on the environment. Hence, the refractory materials are expensive.
The present invention is therefore intended to obviate or at least alleviate the problems encountered in prior art.